Study of the effect of methanol/biodiesel fuel mixtures on the generation of soot particles and their oxidation reactivity

Abstract

When diesel engines burn different fuels, the chemical composition of the emitted combustion particles changes, leading to changes in the oxidation characteristics of these particles and determining the regeneration strategy and service life of after treatment devices. In order to investigate the influence of methanol/biodiesel fuel mixtures on the chemical composition and oxidation activity of emitted soot matter, a test bench was built using a four-cylinder diesel engine, and soot matter in the exhaust was collected. Tests used mixed fuel with different methanol mixing ratios. By using a high-performance liquid chromatograph, a thermogravimetric analyzer, and other equipment, the changes of chemical composition and oxidation characteristics of particles were studied. The results show that as the methanol mixing ratio increases, the mass concentration of organic carbon (OC), bicyclic, and tricyclic polycyclic aromatic hydrocarbons (PAHs) in the particles increase, the mass concentration of elemental carbon (EC) and high molecular weight PAHs decreases, the concentration of nitrate ions first increases and then decreases, the activation energy decreases, and the oxidation activity increases. In general, the chemical composition of combustion particulates from methanol/biodiesel changes, and the oxidation activity is greatly improved. This research work can provide a reference for the coating design and regeneration strategy for optimizing diesel particulate filters (DPFs).